Source/JavaScriptCore/runtime/Symbol.cpp

/*
 * Copyright (C) 2012-2023 Apple Inc. All rights reserved.
 * Copyright (C) 2015-2016 Yusuke Suzuki <utatane.tea@gmail.com>.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "Symbol.h"

#include "JSCJSValueInlines.h"
#include "SymbolObject.h"
#include <wtf/text/MakeString.h>

namespace JSC {

const ClassInfo Symbol::s_info = { "symbol"_s, nullptr, nullptr, nullptr, CREATE_METHOD_TABLE(Symbol) };

Symbol::Symbol(VM& vm)
    : Base(vm, vm.symbolStructure.get())
    , m_privateName(SymbolImpl::createNullSymbol())
{
}

Symbol::Symbol(VM& vm, const String& string)
    : Base(vm, vm.symbolStructure.get())
    , m_privateName(PrivateName::Description, string)
{
}

Symbol::Symbol(VM& vm, SymbolImpl& uid)
    : Base(vm, vm.symbolStructure.get())
    , m_privateName(uid)
{
}

Symbol::Symbol(VM& vm, const String& string, JSString* description)
    : Base(vm, vm.symbolStructure.get())
    , m_privateName(PrivateName::Description, string)
    , m_description(description, WriteBarrierEarlyInit)
{
}

void Symbol::finishCreation(VM& vm)
{
    Base::finishCreation(vm);
    ASSERT(inherits(info()));

    vm.symbolImplToSymbolMap.set(&m_privateName.uid(), this);
}

JSValue Symbol::toPrimitive(JSGlobalObject*, PreferredPrimitiveType) const
{
    return const_cast<Symbol*>(this);
}

JSObject* Symbol::toObject(JSGlobalObject* globalObject) const
{
    return SymbolObject::create(globalObject->vm(), globalObject->symbolObjectStructure(), const_cast<Symbol*>(this));
}

double Symbol::toNumber(JSGlobalObject* globalObject) const
{
    VM& vm = globalObject->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);
    throwTypeError(globalObject, scope, "Cannot convert a symbol to a number"_s);
    return 0.0;
}

JSString* Symbol::toString(JSGlobalObject* globalObject)
{
    VM& vm = globalObject->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);
    if (auto* string = m_string.get())
        return string;

    auto description = tryGetDescriptiveString();
    if (!description) [[unlikely]] {
        throwOutOfMemoryError(globalObject, scope);
        return nullptr;
    }
    auto* string = jsNontrivialString(vm, description.value());
    m_string.set(vm, this, string);
    ASSERT(!string->isRope());
    return string;
}

void Symbol::destroy(JSCell* cell)
{
    static_cast<Symbol*>(cell)->Symbol::~Symbol();
}

template<typename Visitor>
void Symbol::visitChildrenImpl(JSCell* cell, Visitor& visitor)
{
    auto* thisCell = uncheckedDowncast<Symbol>(cell);
    ASSERT_GC_OBJECT_INHERITS(thisCell, info());
    Base::visitChildren(thisCell, visitor);
    visitor.append(thisCell->m_description);
    visitor.append(thisCell->m_string);
}
DEFINE_VISIT_CHILDREN(Symbol);

Expected<String, ErrorTypeWithExtension> Symbol::tryGetDescriptiveString() const
{
    String description = tryMakeString("Symbol("_s, StringView(m_privateName.uid()), ')');
    if (!description)
        return makeUnexpected(ErrorTypeWithExtension::OutOfMemoryError);
    return description;
}

JSString* Symbol::description(VM& vm)
{
    if (auto* string = m_description.get())
        return string;

    auto& uid = m_privateName.uid();
    if (uid.isNullSymbol())
        return nullptr;

    auto* string = jsString(vm, String(uid));
    m_description.set(vm, this, string);
    return string;
}

Symbol* Symbol::create(VM& vm)
{
    Symbol* symbol = new (NotNull, allocateCell<Symbol>(vm)) Symbol(vm);
    symbol->finishCreation(vm);
    return symbol;
}

Symbol* Symbol::createWithDescription(VM& vm, const String& description)
{
    Symbol* symbol = new (NotNull, allocateCell<Symbol>(vm)) Symbol(vm, description);
    symbol->finishCreation(vm);
    return symbol;
}

Symbol* Symbol::createWithDescription(VM& vm, const String& description, JSString* string)
{
    Symbol* symbol = new (NotNull, allocateCell<Symbol>(vm)) Symbol(vm, description, string);
    symbol->finishCreation(vm);
    return symbol;
}

Symbol* Symbol::create(VM& vm, SymbolImpl& uid)
{
    if (Symbol* symbol = vm.symbolImplToSymbolMap.get(&uid))
        return symbol;

    Symbol* symbol = new (NotNull, allocateCell<Symbol>(vm)) Symbol(vm, uid);
    symbol->finishCreation(vm);
    return symbol;
}

} // namespace JSC